1. Field of the Invention
This invention relates, in general, to a method and apparatus for producing rough cut lumber from small diameter wood poles, and in particular, to a method and apparatus for conveying, aligning and holding a pole while it is shaped to form a rectangular beam, and optionally ripping the beam to form rough cut lumber, the disclosed apparatus being easily adjustable for processing poles of varying diameter.
2. Description of the Prior Art
It is well known that there exists in many areas of semi-arid climate, large stands of mature timber having trunks averaging less than 10 inches in diameter. At present, it is usually uneconomic to harvest trees of this size, and after reaching maximum growth, they are inevitably wasted by insect infestation or clear cut and burned. In other more climatically hospitable forested areas, the technique of thinning small diameter trees from a forest of larger trees to reduce the growth competition and stimulate the development of the larger more valuable trees is often practiced. In the past, these small diameter trees have often been cut and left to rot on the forest floor or transported to a central point and burned to clear the forest floor. In the above situations, the small diameter trees have usually not been harvested because the cost of cutting, transporting the raw timber to a sawmill and processing it into lumber has been greater than the market value of the relatively small amount of usable lumber which may be cut therefrom.
Apparatus for processing small diameter logs into lumber and pulp chips for use in the paper industry is known. Apparatus of this type is disclosed in Runnion, Pat. No. 3,259,157 and in Mitten Patents, Nos. 3,313,329; 3,344,826; 3,346,028; 3,442,310; 3,454,063 and 3,487,866.
The Runnion patent relates to large, stationary equipment which chips a previously debarked log into a cross sectionally stepped configuration before sawing it into lumber. Chains are employed above and below the log to both convey it and hold it during chipping.
Mitten, Pat. No. 3,313,329 discloses apparatus substantially different from that disclosed herein limited to the processing of logs having diameters of between 5 inches and 8 inches to form either 4 .times. 4 inch or 4 .times. 6 inch cants.
Mitten, Pat. No. 3,344,826 relates to large, stationary apparatus limited to producing 4 .times. 4 inch cants from peeler cores between 51/2 and 6 inches in diameter, and cannot be adjusted to handle logs of varying size.
Mitten, Pat. No. 3,346,028 relates to the profiling of a log with a cutterhead to produce an improved pulp chip and is concerned primarily with the shape of the pulp chip a consideration of no significance to the instant invention.
Mitten et al., Pat. No. 3,442,310 relates to apparatus for profiling only the bottom and sides of a log, and additionally discloses cutting shallow reentrant reference points on the bottom flat which act as guides in correlating the log to the side cutters.
Mitten, Pat. No. 3,454,063 discloses the use of V-shaped cutterheads to form meeting flats on diametrically opposed sides of a log. No means are disclosed for removing the bark from the log or for holding the log prior to cutting, while V-grooved guides support the log after it has been shaped. Again, as with all the Mitten patents, wood pulp chips are produced from the chordal segments cut away to shape the cant.
Mitten, Pat. No. 3,487,866 discloses holding a log while it is shaped to form a rectangular cant by means of two spaced support grooves cut only in the bottom of the log. A channel shaped shoe is provided to mate with the support grooves, and a chain disposed in said channel is adapted to convey the log past the chip forming cutters. No means for debarking the log is disclosed, nor is any means for adjusting the apparatus to process logs of varying sizes disclosed. The method of supporting a log during shaping disclosed by this patent may be effective with logs of relatively large diameter, such as the 12 inch log discussed therein, in that the support grooves may be cut to a significant depth without entering the later formed cant. In logs of smaller diameter, however, the possible depth of these grooves is limited thereby providing insufficient purchase for the channel shaped shoe to hold the log stable during shaping.